Recent methods have instead been aimed at purifying ambient air and polluted air from other vehicles. U.S. Pat. No. 6,200,542 discloses a method for breaking down ozone. According to the known method, a catalytic coating is applied to the radiator and other surfaces in the engine compartment. When the ozone comes into contact with these surfaces it is converted to oxygen.
A further known method, described in EP 1082990, uses a HC trap adjacent to the radiator for adsorbing pollutants from the ambient air while the vehicle is moving. The adsorbing process is followed by desorption by passing heated intake air through the trap to an intake conduit of the engine. This apparatus is operated when the vehicle is moving.
However, none of the known methods disclose a method for using the ventilation system for cleaning ambient air by adsorption of hydrocarbons while the vehicle is either stationary, with the ignition switched off, or moving, combined with desorption and combustion of hydrocarbons when the vehicle is moving.
In addition, both known apparatuses are directly exposed to a flow of ambient air and will be sensitive to particles of dirt, tarmac and dust settling on the active surfaces.